Method of manufacturing continuous coated sheets of paper, film, or the like



, Aug. l, 1939. R E sMrrH E1- AL 2,168,051

. METHOD oF HANUFAOTUFRING CONTINUOUS COATED srms'rs OF PAPER, FILM, ORTHO LIKE Filed Aug. 28! 1936 Patented Aug. 1,1939

UNITED STATES METHOD OF MANUFACTURING CONTINU- OUS COATED SHEETS F PAPER, FILM,

LIKE

on THE Robert E. Smith and Karl T. Molln, Rochester,

. Y., assig'norsV to Defender Photo Supply Company, Incorporated,. Rochester, N. Y., a corporation of New York ApplicationAugust 28, 1936, Serial No. 98,42

1 Claim. (Cl. 91-69) This invention relates to a method of manufacturing continuous coated sheets of paper, iilm or the like, and has to do more particularly with the treatment of light-sensitive coatings on photographic paper or lm.

One object of the invention is to treat the wet colloidal, gelatin, or other light sensitive coating on a continuous sheet or base, after the coating is partially set and before applying heat for drying, so as to remove from the coating a substantial amount of the solvent or water, thereby reducing the amount of water to be removed by evaporation and les'sening the time required in the heat drying operation and the amount of heat to be applied to the coating and base.

-A further purpose of the invention is to produce a superior photographic paper or iilm, due to subjecting the paper' and coating to heat drying over a shorter period of time than heretofore 20. and causing the sheet to travel a shorter distance during drying, thus reducing the possibility of defects in the photographic paper or lm,`improving its quality, and increasingy the effective life of the product. 1

Heretofore in the manufacture of photographic 25 paper' or lm, the general practice has been to set the gelatin, coating or emulsion partially, as` by passing the sheet through a cooling chamber, and

then to carry Ythe sheet through drying rooms or chambers where the ymoisture is evaporated by successively subjecting it to progressively hotter currents of heated air, and it is a purpose of this invention to remove from the coating a large portion of the moisture or solvent, after the coating is initially set and before it is subjected to the 'heat drying operation. This is accomplished by applying, in a suitable manner to the coating, a uid, or liquid, such as alcohol, having .a high ailinity for the solvent or water in the coating, and then removing from the surface of the coat- 40 ing the alcohol and solvent which it has extracted by any suitable means, such asa squeegee, roller, scraper, -or air blast, so thatwhen the coated sheet reaches the heat'drying chamber, a considerable amount of moisture has been removed and correspondingly less time and heat is required in the heat-evaporating stage of the operations.

To these and other ends, the invention includes the method that will appear more clearlyfrom 50 the following description when readin conjuncfeatures-being pointed out in the claim following the specication.

In the drawing: 55 Fig. 1 is a diagrammatic View illustrative of proved method as applied to photographic paper orlm having a single coating of light-sensitive emulsion;

Fig. 2 is a diagrammatic view snowing another tion with the accompanyingl drawing, the novelone form of apparatus for carrying out the im form of apparatus for treating photographic paper or iilm having a second protective coating applied over a light-sensitive coating, and

' v Fig. 3 is a diagrammatic view of a further modification of apparatus for treating photographic paper or lm having a protective coating applied over a light-sensitive coating.

The invention is applicable to the manufacture of any continuous coated sheet or base, and the present disclosure, which is merely illustrative-of some practical examples of its use, shows how it may be adapted to the manufacture of photographic paper or film.

Referring to Fig. 1, the sheet or base or support is designated at I, and isfed from a supply ro1l.2, whence it travels around guide rolls 3 and 4 into a tank 5 containing a light-sensitive coating, usually in the form of a gelatin emulsion containing light-sensitive salt, such` as halides of silver, which is applied to the exposed surfaceof the sheety I.

The latter thereupon travels around guide rolls 6 and 'I and thence through a cold air chamber y 8 having an inlet 5 and outlet I0 for refrigerated air, to bring about the initial setting of the coating on the sheet.

After the coating is initially set, and before it 'reaches the heat drying chamber, provision is made for removing a part of the solvent' from the coating by spraying or otherwise applying to the coating a uid or liquid having a high aflinity for the water or solvent in the coating. To this end, after leaving the cold air chamber 8, the sheet-I travels around a guide roll II located in a tank I2, where the sheet or film, with the emulsion coating partially set thereon, is passed through a bath of liquid, such as methyl or ethyl alcohol, having a high ainity for the solvent or l water in the emulsion coating. This liquidon the coating attracts the water or solvent in the coating, withdrawing a large part of it from the body of the coating to the surface thereof, and into .the superposed layer of alcohol, where it can be removed by suitable means, as will be described presently.

The sheet or support I thence travels through a cold air chamber I3 having an inletl I4 and outlet I5 for refrigerated air, causing a further setting of the emulsion coating on the lm, following which the sheet travels around a guide roll I 6, at which point it is preferably subjected to the action of the liquid removing means, which may be of any convenient form, such as a squeegee, roller, scraper, or air blast, which are comvDrehended by mechanical pressure inthe claim, as distinguished from evaporation or drying. The

l5o o `move from it the alcohol, or superposed layer of Whatever liquid may be employed for the purpose, together with the water or solvent that has been removed from the coating and is combined with the alcohol.

When methyl or ethyl alcohol is used, it chills the gelatin in the emulsion, and tends to precipitate thegelatin, hastening the setting and causing the gelatin coating to become hard and resistant to surface abrasion, and no further cooling of the coating is required before subjecting the sheet to the nal heat drying operation. The

sheet thereupon passes around a guide roll I8 i and thence to the drying chamber or room, as usual in this class of apparatus, where it is subjected to hot air currents to evaporate the remaining moisture from the sheet and coating and effect complete drying thereof.

'I'he alcohol may be sprayed onthe surface of the coating, as shown in'Fig.,2, instead of carrying the sheet through the liquid as in Fig, 1, and the invention may be applied to a sheet having a light-sensitive coating and a second protective coating, as shown in Figs. 2 and 3.

In the construction -shown in Fig. 2, the

arrangement of the parts and the treatment of.

the sheet is the'same as in the Fig. 1 construction up to thepoint where it passes throughgthe cooling chamber il.` Following this, the sheet l is passed around a guide roll 20 located in a tank 2| which, contains a protective coating of'plain gelatin or like substance such as used for protective coatings-in the manufacture of photographic film and paper, and thereafter the sheet is carried through a cooling chamber 22 having an inlet 23 and outlet 2l for refrigerated air currents. 25 designates a sprayer to be supplied with methyl or ethyl alcohol, or other liquid having a high ailinity for the water lor solvent in the coating, andsuch liquid is preferably sprayed on to the surface of the protective coating at this point, the coatings having previously been partially set by movement through the cooling cham- 'Ihereafter the sheet passes around the guide roll 26 and is subjected to the action of the liquid removing means preferably in the form ,Y of al sheet is carried around the guide roll 28 and:

thence to the drying room or chamber where it is subjected to currents of air sufficiently heated to bring aboutl the evaporation of the remaining moisture in the coatings and nal drying.

In Fig. 3 is illustrated a modied arrangement for drying a double coated sheet by dipping it in a liquid bath instead of spraying the liquid thereon, as in Fig, 2. With this arrangement, the sheet is dipped in a protective coating emulsion in the tank 2 9, after which it travels through the cooling chamber 30, around the guide rolls 3| and 32 and is thence carried a second time through the cooling chamber 33 which has an inlet 34 and outlet 35 for refrigerated air currents. After leaving the cooling chamber 33, the sheet travels around a guide roll 36 at which point it passes through the tank 31 containing the alcohol or other liquid,

which has the requisite solvent-withdrawing effect upon the coating. The sheet travels thence through the cooling chamber 38 having an inlet 39 and outlet 40 for the refrigerated air currents, and thence around the guide roll 4I at which point the outer surface of the protective coating is subjected to the action of liquid removing means which may consist of 'a squeegee 42 or other suitable instrumentality that removes the surface liquid together with the solvent that has been withdrawn from the coatings. After this the sheet travels around the guide roll 43 and thence to the drying room or chamber where the final drying operation is effected. Any suitable apparatus may be employed for collecting the alcohol after it has been 'removed from the coating, and this may be recovered from the solution by distillation or other suitable method and again used. A

With this process, a considerable saving in the `cost of manufacture is possible, due to the reduced refrigerating and drying requirements, This greatly lessens the cost of the necessary heating and air-circulating equipment in the production of photographic papers and lhn, and also reduces the oor space required in such manufacturing processes..

In addition to substantial savings in the manufacturing cost, the invention, also results in a superior product, since the extreme heat required in previous drying methods results in shortening the life of such products. By lessening the amount of heat to which the product must be subjected during its manufacture, and by shortening the time during which it is exposed to air while wet, the effective life of the product is lengthened and its qualityv greatly enhanced.

As a result, the light-sensitive coating will retain its desirable properties longer, drying marks are eliminated from the finished product, a greater uniformity of photographic quality is had, improved color in paper coated with warm tone emulsions is,effected, there is less tendency for Vthe .product to curl, or expand and contract dur- 'ing drying, and the possibility of defects caused by chemical or physical action of impurities in the sheet or in the surrounding atmosphere during the drying operation is greatly reduced.

The invention may be carried out in ways and with apparatus other than that particularly set forth, and this application is intended to cover any adaptations or applications of the improvement coming within the intent of the method -herein disclosed or the scope of the following claim,

We claim:

'I'he method which consists of the following steps, namely, first applying a water-containing light sensitive coating. to a continuous sheet, secondly applying to the surface of said coating' a highly concentrated liquid alcohol which acts to harden the coating partially and to extract a, portion of the water from the body of t-he coating to the surface thereof, thirdly, partially drying the coating by removing a major part of said surface alcohol and water byapplying mechanical pressure tothe surface of the coating, and finally drying the sheet and coating by evapo- 

